code: def _mean_characters_per_word(value):
      if pd.isna(value):
          return np.nan
  
      # replace end-of-sentence punctuation with space
      value = END_OF_SENTENCE_PUNCT_RE.sub(" ", value)
      words = value.split()
      character_count = [len(x) for x in words]
  
      return np.mean(character_count) if len(character_count) else 0
  
file_path: featuretools/featuretools/primitives/standard/transform/natural_language/mean_characters_per_word.py
imports: import re
  import numpy
  import pandas
  from woodwork.column_schema import ColumnSchema
  from woodwork.logical_types import Double, NaturalLanguage
  from featuretools.primitives.base import TransformPrimitive
label_desc: Use image node_id 1 for calling a global function with example usage: _mean_characters_per_word(value) and returns: unknown, np